Buying New Bike - Questions on Suspension Travel

I'm currently riding a 10 year old dual suspension bike that has 4.76" rear travel and a 3.10" fork (per spec sheet...I bought it used three years ago for $100 and have ridden the crap out of it). I'm in the market for a new bike and rode both 5" travel and 6" travel bikes. A 5" travel bike is enough for my local trails that I will be riding most often, but I have gnarly trails within one to two hour's drive and plan to ride those as well. In addition, I will be traveling to Colorado a few times a year and plan on taking my bike and ride the trails there as well.

When I demo'd them, I liked both bikes. Would you recommend I get the 6" travel bike, since I will be needing the extra travel the times I drive to other trails and when I fly to Colorado or get the 5" travel bike and suck it up on the gnarly trails? Your thoughts??

Travel is only part of the picture. Frame geometry, and wheel size is very important as well.
What bikes exactly are your looking at. I have a 5 inch travel, 26" trail bike(Marin MV) and I can take it to all but super gnarly downhill trails.

Travel is only part of the picture. Frame geometry, and wheel size is very important as well.
What bikes exactly are your looking at. I have a 5 inch travel, 26" trail bike(Marin MV) and I can take it to all but super gnarly downhill trails.

I left the bike's brand out to avoid brand bias, but they both have 27.5 wheels. I want to avoid the brand debate and focus on independent comments. Thanks for all that have replied. Keep them coming.

Big generalization here, but most likely the 5" bike will pedal better and be more efficient climbing and on rolling trails than the 6" bike? 5" of a new bike will be far superior to the 4.75" inches you have on your current bike, amplified by 27.5" instead of 26". Finally, even in Moab, I have never felt like the 4.6" of travel on my 29"er was what was holding me back. My feeling would be that I would get the 5" bike since that will excel more for you the vast majority of the time that you ride, and unless you are planning on doing super gnarly, freaky, DH-only type trails in Colorado, you don't NEED a 6" bike out there either. In fact, the 5" bike will probably pedal better uphill, which will be of benefit out in Colorado!...
Now the above is assuming that you are comparing equally well-designed 5" and 6" bikes (ie, similar suspension geometries and pedal platforms and similar frame materials, components, etc).
So all that said - have you had a chance to real test ride both bikes on your trails? If so, which did you like better and why? I'd put my money on that one.

Buying New Bike - Questions on Suspension Travel

I left the bike's brand out to avoid brand bias, but they both have 27.5 wheels. I want to avoid the brand debate and focus on independent comments. Thanks for all that have replied. Keep them coming.

Unfortunately, you left out the most important piece of info, brand and model. For example, yeti 575 though has more travel than ibis mojo but lean more xc than am trail not to mention bigger bike in the same size.

My ibis mojo hd can be both 6.3" and 5.5" as well as 26 and 650b(27.5"). Longer travel usually doesn't yield as good climbing performance as shorter ones but not always my maverick ml8 has 6.5" rear travel also equipped with hamerschmidt which adds about 2 extra pounds, yet it's the best climber I own or have tried so far.